Interests in energy storage technologies have been increasingly higher recently. As applications are expanded to energy of mobile phones, camcorders and notebook PCs, and furthermore, to electric vehicles, efforts on the research and development of electrochemical devices have been more and more materialized.
Electrochemical devices are fields receiving most attentions in such aspects and among these, development of secondary batteries capable of charge and discharge have been the focus of attention, and in developing such batteries, research and development on the design of new electrodes and batteries for enhancing capacity density and energy efficiency have been recently progressed.
Among currently used secondary batteries, lithium secondary batteries developed in early 1990s have received attentions with advantages of having high operating voltage and significantly higher energy density compared to conventional batteries such as Ni-MH, Ni—Cd and sulfuric acid-lead batteries using an aqueous liquid electrolyte.
A lithium secondary battery is generally formed by an electrode assembly including a positive electrode, a negative electrode and a separator provided between the positive electrode and the negative electrode being embedded in a battery case in a laminated or wound structure, and a non-aqueous liquid electrolyte being injected thereinto.
As for a lithium electrode as the negative electrode, lithium foil attached on a planar current collector is used. In this case, lithium formation and elimination are irregular when charged and discharged producing lithium dendrite, and this leads to continuous capacity decline.
In view of the above, studies introducing a polymer protective layer or inorganic solid protective layer to a lithium metal layer, increasing a salt concentration of a liquid electrolyte, or using proper additives have been progressed. However, effects of suppressing lithium dendrite resulted from such studies are insignificant. Accordingly, solving problems through modifying a form of a lithium metal negative electrode itself or modifying a battery structure may be an effective option.